Almost all of the nations are crazy rich. However, the richest countries are the East Asians + Singapore. Europe's economy is constantly in shambles (mostly from all the wars they do) so they're poorer than North America and Asia, but they are richer than South America, Africa, Antarctica and Oceania. Trillions of money are like nothing to them, they're far too used to seeing that much money. They live in mansions/manors and have lots of fancy expensive stuff (Yachts, thousands of houses in each and every city, etc.) The Asians, most specifically East Asians are definitely on a whole other level of rich. They are practically drowning in multibillions. Singapore is right behind them in terms of money. East Asia houses the largest and most prosperous economies, their knack for invention and amazing business skills resulted in what they call "economic miracles" and became the richest. Even the youngsters like Yung Soo, Leon, and Mei are part of it too.
The East Asia nations pride themselves on their money and modernity (Kiku being much more humble about it though) and would stay in the most expensive hotels, buy the most expensive things, go to the most expensive places, etc. They are the type to flex their money on people. Once again, Singa joins them in this, however he mostly flexes his riches to his fellow ASEAN, who admire him.